1. Technical Field
The present invention relates to an image verification device that checks an image obtained by photographing an object against an image database, an image processing system, an image verification program, a computer readable recording medium, and an image verification method.
2. Related Art
A conventional face authentication technique that registers an image obtained by preliminarily photographing a human face in a database and, depending on an input of an image obtained by photographing the face of a person to be recognized, and compares the input image with registration contents of the database to identify individuals from each other so as to make authentication is known.
An authentication process in the face authentication technique illustratively includes a registration process and an authentication process. A concrete example will be described below.
In registration, from an image obtained by photographing the face of a person, an amount of feature representing characteristics of the face of the person are extracted and registered in advance. On the other hand, in authentication, the amount of feature is extracted from an input image. The amount of feature extracted from the input image is compared with an amount of feature registered in a database to calculate an authentication score. The authentication score is evaluated to determine whether the input image is matched with an image registered in the database.
Here, in the case where persons who have a relationship such as brothers or children and parents and have similar faces are registered, an approximate authentication score tends to be calculated between the persons. For this reason, it is known that erroneous authentication easily occurs during authentication. More specifically, when an input image is simply compared with the image of a person registered in a database, erroneous authentication may occur between registered persons having similar faces.
In order to prevent the erroneous authentication, various techniques have been proposed. For example, Patent Document 1 discloses that registered data of persons having similar faces are grouped to set threshold values depending on the groups in evaluation of authentication scores.